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/*
 * Copyright 2000,2005 wingS development team.
 *
 * This file is part of wingS (http://wingsframework.org).
 *
 * wingS is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * Please see COPYING for the complete licence.
 */
package org.wings.plaf.css;


import org.wings.*;
import org.wings.session.ScriptManager;
import org.wings.io.Device;
import org.wings.plaf.css.script.LayoutFillScript;
import org.wings.plaf.css.script.OnPageRenderedScript;
import org.wings.plaf.Update;

import java.io.IOException;

public class FormCG extends AbstractComponentCG implements org.wings.plaf.FormCG {

    private static final long serialVersionUID = 1L;

    @Override
    public void writeInternal(final Device device, final SComponent component) throws IOException {
        final SForm form = (SForm) component;
        SLayoutManager layout = form.getLayout();

        // Prevent nesting of forms
        boolean formTagRequired = !form.getResidesInForm();

        if (formTagRequired) {
            // Is there a default button?
            String defaultButtonName = "undefined";
            if (form.getDefaultButton() != null) {
                defaultButtonName = Utils.event(form.getDefaultButton());
            }
            StringBuilder script = new StringBuilder();
            script.append("wingS.update.defaultButtonName('").append(defaultButtonName).append("');");
            ScriptManager.getInstance().addScriptListener(new OnPageRenderedScript(script.toString()));

            device.print(" in
            // any of its fields. In all other cases - i.e. if a
            // button is clicked - the affected component fires its
            // "onclick"-event which calls "sendEvent(...)" which in
            // turn submits the form VIA JAVASCRIPT (either by means
            // of Ajax or the traditional way). Whenever forms are
            // submitted via JS (e.g. form.submit()) the "onsubmit"-
            // handler is NOT triggered. So once again, the code below
            // will only be executed when  has been pressed.
            //
            // Therefore we can use this mechanism in order to handle
            // the default button of the form. (see SessionServlet)
            device.print(" onsubmit=\"wingS.request.sendEvent(");
            device.print("event,");
            device.print("true,");
            device.print(!component.isReloadForced());
            device.print(",'default_button', wingS.global.defaultButtonName); return false;\">");

            writeCapture(device, form);

            // This code is needed to trigger form events
            device.print("");
        }

        SDimension preferredSize = form.getPreferredSize();
        String height = preferredSize != null ? preferredSize.getHeight() : null;
        boolean clientLayout = Utils.isMSIE(form) && height != null && !"auto".equals(height)
            && (layout instanceof SBorderLayout || layout instanceof SGridBagLayout);

        String tableName = form.getName() + (formTagRequired ? "_table" : "");
        device.print("");

        // Render the container itself
        Utils.renderContainer(device, form);

        device.print("");

        if (formTagRequired) {
            writeCapture(device, form);
            device.print("");
        }
    }

    /*
     * we render two icons into the page that captures pressing simple 'return'
     * in the page. Why ? Depending on the Browser, the Browser sends the
     * first or the last submit-button it finds in the page as 'default'-Submit
     * when we simply press 'return' somewhere.     *
     * However, we don't want to have this arbitrary behaviour in wingS.
     * So we add these two (invisible image-) submit-Buttons, either of it
     * gets triggered on simple 'return'.
     *
     * Formerly this mechanism was also used for the default button handling of
     * the form. This is now done further above by the "onsubmit"-handler. However,
     * we still need theses two images in order to always get the latter invoked.
     *
     * Watchout: the style of these images once had been changed to display:none;
     * to prevent taking some pixel renderspace. However, display:none; made
     * the Internet Explorer not accept this as an input getting the default-focus,
     * so it fell back to the old behaviour. So changed that style to no-padding,
     * no-margin, no-whatever (HZ).
     */
    private static void writeCapture(Device device, SForm form) throws IOException {
        // Whenever a form is submitted via JS (like done in this case - see above)
        // a input field of type image (like the one below) won't be sent. This is
        // because for some reason it doesn't belong to the "form.elements"-collection
        // which is eventually used to assemble the post-parameters. That's why we
        // don't even name it - would be useless anyway...
        device.print("");
    }

    @Override
    public Update getEncodingUpdate(SForm form, String encoding) {
        return new EncodingUpdate(form, encoding != null ? encoding : "");
    }

    @Override
    public Update getMethodUpdate(SForm form, String method) {
        return new MethodUpdate(form, method != null ? method : "");
    }

    @Override
    public Update getDefaultButtonNameUpdate(SForm form, String defaultButtonName) {
        return new DefaultButtonNameUpdate(form, defaultButtonName != null ? defaultButtonName : "undefined");
    }

    protected static class EncodingUpdate extends AbstractUpdate {

        private String encoding;

        public EncodingUpdate(SComponent component, String encoding) {
            super(component);
            this.encoding = encoding;
        }

        @Override
        public Handler getHandler() {
            UpdateHandler handler = new UpdateHandler("encoding");
            handler.addParameter(component.getName());
            handler.addParameter(encoding);
            return handler;
        }
    }

    protected static class MethodUpdate
        extends AbstractUpdate {

        private String method;

        public MethodUpdate(SComponent component, String method) {
            super(component);
            this.method = method;
        }

        @Override
        public Handler getHandler() {
            UpdateHandler handler = new UpdateHandler("method");
            handler.addParameter(component.getName());
            handler.addParameter(method);
            return handler;
        }
    }

    protected static class DefaultButtonNameUpdate
        extends AbstractUpdate {

        private String defaultButtonName;

        public DefaultButtonNameUpdate(SComponent component, String defaultButtonName) {
            super(component);
            this.defaultButtonName = defaultButtonName;
        }

        @Override
        public Handler getHandler() {
            UpdateHandler handler = new UpdateHandler("defaultButtonName");
            handler.addParameter(defaultButtonName);
            return handler;
        }
    }
}